Eko Hoshunin is the Karas series primary antagonist.
He is Shinjuku's Karas and because he stands for other reasons than to protect the city Shinjuku makes another Karas. He has been a Karas for over 400 years and it's said that he was around since the Edo time period. He is the leader of the Mikura army.
In the final battle, Ekou is eventually put to rest by Yousuke Otoha.
At the end of the credits of "Karas: The Revelation," Eko's golden boot is seen in the Shinjuku sewers. It is unknown on who was looking at the boot in the sewers.